Headers for a crop harvesting machine generally comprises a main longitudinal support member in the form of an elongate tube which extends across substantially the full width of the header frame and defines a main structural member for the header frame. The tube carries a plurality of forwardly and downwardly extending support beams which include a first portion extending downwardly and a second portion attached to a lower end of the first portion and extending forwardly therefrom toward a forward end of the support beams. The cutter bar is attached to the forward end of the support beams and is thus held thereby in a position generally parallel to the main support tube.
Many headers are of a type in which the cutter bar is intended to be in a fixed rigid position relative to the main support tube so that the cutter bar is not intended to flex or float relative to the main structural tube in response to changes in ground contour.
This rigid type of header has the advantage that it allows more accurate control of the position of the fingers or bats of the reel relative to the cutter bar so as to more accurately control the crop as it is swept onto the cutter bar and the table rearwardly of the cutter bar.
In this rigid header type, therefore, the support beams extending forwardly from the main structural tube are substantially rigid and hold the cutter bar in fixed position.
Alternative types of header mount the cutter bar for floating or flexing movement relative to the main structural support tube. This type of header is used to provide an improved action in following the contour of the ground and is advantageous in some circumstances. Thus when cutting crops right at the ground it is desirable that the cutter bar of larger headers, greater than of the order of 20 feet, is somewhat flexible to follow the ground contour. This type of header however has the disadvantage that the flexing or floating of the cutter bar relative to the main support tube causes movement of the cutter bar relative to the bats or fingers of the reel so that it is no longer possible to maintain a close tolerance between the bats or fingers and the cutter bar.
Various manufacturers provide a flexing cutter bar structure for example the Soybean Header manufactured by Case IH under the Model No 820 or 1020.
Another type of header provides a cutter bar which is relatively rigid but can float upwardly and downwardly relative to the main structural support tube of the header. This type of header again is used to allow close floating-action of the cutter bar on the ground surface and one example is shown in the “Dial-a-matic Header Height Control” available for various Deere and Company combine harvesters. This floating action of a cutter bar however occurs relative to the main structural tube and therefore relative to the reel so that the cutter bar to reel co-operation cannot be optimized.
It is known that rigid headers are conventionally flexibly mounted to the propulsion machine, that is a swather tractor, combine harvester or pull type frame, and the header as one piece can generally follow the ground contour while the cutting knife remains rigid.
It is also known that headers of this type can be controlled so that they rotate around an axis at a center of the header in response to sensors which detect ground height so as to maintain the sides of the header as close to the ground as possible.
When cutting above the ground, a header of this type with a rigid knife structure is most effective because the rigid knife structure allows maximum cutting speed and thus an improved cutting action.
When cutting on the ground with larger headers, it is known to have a cutter bar which is mounted on the header so that it can flex or float across its width relative to the ground. Examples of such flexible cutter bars are shown in U.S. Pat. No. 4,665,685 (Rupprecht) issued May 19, 1987 and U.S. Pat. No. 4,875,331 (Ostrup) issued Oct. 24, 1989. Both of these arrangements show a cutter bar which is mounted on a skid and thus skids across the ground and flexes across its whole width to accommodate changes in height of the ground.
One disadvantage of the conventional flexible cutter bar is that it may in some designs require a significantly reduced cutting speed since the reciprocation of the conventional sickle knife must be reduced in velocity to accommodate the curvature of the cutter blade which can occur when the whole of the cutter blade is flexible. Conventionally a flexible cutter bar of this type can flex as much as a total of five to six inches to accommodate the changes in ground height which occur relative to the fixed part of the header frame which remains fixed and does not change relative to ground height.
A further disadvantage of a flexible cutter bar of this type is that it is necessary to set the reel at a height which accommodates the upward movement of the cutter bar which can occur. The reel fingers therefore must necessarily be spaced a significant distance from the cutter bar to avoid the possibility that the raised cutter bar interferes with the fingers and causes damage to either or both. This increased distance between the fingers of the reel and the cutter bar can cause irregular or improper feed of the crop material over the cutter bar particularly in light crop conditions so that an accumulation of cut crop on the cutter bar can eventually halt further cutting action leaving a part of the crop uncut and thus unharvested.
The disadvantage of the rigid cutter bar design is that rather than floating over a small area like a ridge or gopher mound, the rigid header pushes dirt in front of the sickle knife which impedes cutting and allows dirt to enter the header with the crop.
Up till now, therefore, the rigid header arrangement with its accurate reel finger to cutter bar location is not fully satisfactory as it cannot accurately follow ground contour; and the flexible cutter bar design, which can follow ground contour, is also not fully satisfactory in view of the increased and varying space between the reel fingers and the cutter bar.
In U.S. Pat. No. 4,956,966 (Patterson) issued September 1990 and assigned to the present Assignee is disclosed a header which includes drapers for transporting the crop inwardly from the sides of the header toward the central discharge section. The use of drapers can provide an arrangement which allows the header table to flex although the arrangement shown in the patent and the product manufactured in accordance with the patent provides a rigid header of the type described above. The header of Patterson includes a central link by which the position of the upper end of the header can be pulled toward or released from the supporting vehicle so as to change the angle of the frame of the header about an axis across the width of the header. A skid plate can be provided just behind the cutter bar which can run across the ground so that the change in angle of the header changes the angle of the cutter bar in front of the skid plate.
In U.S. Pat. No. 5,464,371 (Honey) issued November 1995 to Honeybee Manufacturing is disclosed a draper header of a type similar to that disclosed in Patterson.
In U.S. Pat. No. 4,446,683 (Remple) issued May 1984 to Canadian Co-operative Implements is disclosed a header for a swather which includes a central section and two wing sections in which the wing sections can pivot about a forwardly extending axis to allow the outer ends of the wing sections to be raised to a height as much as six feet from the ground. The cutter bar is continuous through the pivot axes so that the cutter bar flexes as the hinging action occurs. The patent led to development of a product manufactured by the above company which utilized the arrangement of the wing sections and the flexible cutter bar. There were a significant number sold but it is not being built any more and the arrangement is no longer commercial. The device supported the center section on the swather tractor but the wing sections were supported upon individual ground wheels mounted at the ends of the wing sections. It is necessary therefore to control the height of the wing sections by actuating movement of the ground wheels and this arrangement therefore did not allow the system to accurately follow the ground contour.
In U.S. Pat. No. 4,409,780 (Beogher) issued October 1983 to Kansas State University is disclosed a header with three independent sections so that two wing sections can be folded rearwardly for transport. However this arrangement does not provide a flexible arrangement which allows the cutter bar as a whole to accurately follow the ground contour.
In U.S. Pat. No. 6,675,568 (Patterson) issued Jan. 13, 2004 to the present Assignees is disclosed a crop harvesting header for mounting on a propulsion vehicle such as a swather tractor or combine harvester which includes a main frame structure supporting a crop receiving table with a cutter bar across a front of the table and side drapers on the table for moving the cut crop toward a discharge location of the header. The frame is divided into a central frame portion and two separate wing frame portions each arranged for pivotal movement relative to the central portion about a pivot axis extending in a plane parallel to the forward direction and intersecting the cutter bar so that, as the wing frame portions pivot, the cutter bar flexes in the area adjacent the respective pivot axis over a small angle of the order of 4 degrees to maintain the cutter bar following the ground. The central frame portion is mounted on two spring arms for upward and twisting floating movement such that the total downward force on the ground, from that part of the weight of all of the portions of the header which is unsupported, can be varied by moving the support to change the total pressure of the header on the ground. The wing frame portions are connected to the central frame portion by interconnecting linkages which transfer weight from the wing frame portions to the springs of the central portion each including a respective balance beam arranged to balance the lifting force from the spring with the downward forces from the center portion and wing frame portion such that the downward force on a skid plate of each portion on the ground varies automatically as the total downward force is varied.